1. Field of the Invention
This invention generally relates to infusion of resin into a woven textile and particularly relates to hot-melt infusion into three-dimensional, woven, textile preforms.
2. Description of the Prior Art
Generally, laminating resins are used as the matrix material in woven textiles., this also being true for woven preforms used to connect components made of composites or other materials. An example of a commonly-used laminating resin is 977-3, available from Cytec Industries, Inc., of West Paterson, N.J. Typically, the laminating resin is filly infused into a textile product, wetting all of the fiber bundles in the preform and forming a xe2x80x9cprepreg,xe2x80x9d or pre-impregnated textile. The resin is later cured to form a polymer matrix in the finished composite component. Methods of fully impregnating flat textiles include immersing in a solution, pressing with rollers, and pulling through a die. All of these methods have the advantage of being able to do continuous lengths.
In solution impregnation, the resin is dissolved in a solvent, and the textile is immersed in the solution. The textile is then removed from the solution, and the solvent is evaporated, leaving the resin in the textile. The disadvantages of this method are that resin content is difficult to control and that the volatile gases must be removed.
FIG. 1 shows a prior art method of infusing resin into a textile 11 by placing resin film 13 against textile 11 and feeding them between a pair of heated rollers 15. Rollers 15 heat and press resin 13 into textile 11, transferring the resin 13 into textile 11.
FIG. 2 shows a second prior art method of infusing resin. The pultrusion method of infusing a textile 17 with resin 19 involves pulling textile 17 through a heated die 21. Resin 19 is placed against textile 17, and these are fed into the die to heat resin 19 and infuse textile 17. Die 21 may also cure resin while textile 17 is within die 21.
While these techniques work well for flat textiles, infusion of three-dimensional textile preforms presents different problems. The prior-art methods described above may be used to fully infuse 3-D preforms, but the preforms may have too much resin at intersections, causing the preform to be overly bulky in those areas. Also, a fully-infused preform tends to be stiff and less pliable, making the preform difficult to handle or position during assembly.
A method provides for full or partial infusion of resin into three-dimensional, woven, textile preforms. Resin film is placed at selected locations adjacent the preform, and the resin film may be separated from other areas of the preform using separator sheets or other materials. The preform is heated and may be vacuum-bagged to apply pressure, or may be rolled or fed through a die. The heat and pressure cause the resin to infuse into the selected areas of the preform adjacent the resin films. The amount of resin in the partial infusion is the same as is necessary to fully infuse the preform, but the resin remains localized in the selected areas until heated again at cure to cause the resin to flow throughout the preform. The method may also be used to fully infuse the preform with resin by providing sufficient temperature and time at that temperature during the initial infusion.